Australian Centre for Advanced Photovoltaics Australia-US Institute for Advanced Photovoltaics Annual Report 2017 Stanford University Table of Contents 1. Director’s Report 1 2. Highlights 3 Record Cu2ZnSnS4 (CZTS) solar cells 3 High-efficiency four-terminal CZTS/Si and CIGS/Si tandem cells by spectrum splitting 3 High performance perovskite – silicon tandem cells 3 Record perovskite cell efficiency 4 Polysilicon passivated contacts with 735 mV implied-Voc and low contact resistance 4 Record open circuit voltage for Cz silicon solar cell 5 High Impact Papers 5 Distinguished scholar Professor Henry Snaith visits Monash University and UNSW Sydney 6 Andrew Holmes AC 6 Dr Brett Hallam, NSW Premier’s Award for Energy Innovation 6 A/Prof Renate Egan lauded as one of Eight Great Women in the Business and Science of Solar 6 EU PVSEC Student Award for UNSW’s Appu Rshikesan Paduthol 7 Awards and front covers for Monash PhD student Wenxin Mao 7 Congratulations to Mathias Rothmann 7 3. Organisational Structure and Research Overview 8 4. Affiliated Staff and Students 10 University of New South Wales 10 Australian National University 11 CSIRO Manufacturing 12 University of Melbourne 12 Monash University 12 University of Queensland 13 QESST 13 National Renewable Energy Laboratory 13 Molecular Foundry, Lawrence Berkeley National Laboratories 13 Stanford University 13 Georgia Technology Institute 13 Wuxi Suntech Power Co. Ltd. 14 Trina Solar 14 BT Imaging 14 BlueScope Steel 14 PV Lighthouse 14 Dyesol/Greatcell 14 Raygen 14 ii — Australian Centre for Advanced Photovoltaics 5. Research Reports 15 Program Package 1 Silicon Solar Cells 15 PP1.1 Solar-grade silicon 16 PP1.2a Rear contact silicon cells 17 PP1.2b Passivated contacts 18 PP 1.3a Silicon tandem cells (monolithic) 19 PP1.3b Silicon tandem cells (mechanically stacked) 30 Program Package 2 Thin-Film, Third Generation and Hybrid Devices 32 PP2.1 Organic Photovoltaic Devices 32 PP2.1b Organic Tandem Solar Cells 42 PP2.2 CZTS solar cells 45 PP2.4a Hot Carrier Cells 52 PP2.4b Silicon Nanostructure Tandem Cells 54 PP2.5 Perovskites 56 Program Package 3 Optics and Characterisation 70 PP3.2 Plasmonic and Nanophotonic Light Trapping 70 Program Package 4 Manufacturing Issues 74 PP4.1 Cost Evaluations 74 PP4.2 Life Cycle Assessments 78 Program Package 5 Education, Training and Outreach 81 6. AUSIAPV International Activities 88 6.1 Improved Sunlight to Electricity Conversion Efficiency: Above 40% for Direct Sunlight and Above 30% for Global 89 6.2 Dye-Sensitised Solar Cells 91 6.3 Carrier Selective Contacts for Boosting Silicon Solar Cell Efficiency 92 6.4 Solar Cell Performance Documentation 93 6.5 PV Manufacturing Education 94 Collaboration Grants 95 7. Financial Summary 100 8. Publications 101 8.2 Book Chapters 101 8.3 Patent Applications 101 8.4 Papers in Refereed Scientific and Technical Journals 101 8.5 Conference Papers and Presentations 110 8.6 Theses 114 Obituary Professor Stuart Ross Wenham 116 Annual Report 2017 — iii 01 – Director’s Report economy away from hydrocarbons. Masdar and its French partner EDF submitted an offer of US$17.86/MWh, lower than even the short- run marginal cost of generation from most existing Australian black coal plants. Australia has played a major role in achieving these past cost reductions and is expected to play a key role in future cost reductions through the activities of the Australian Centre for Advanced Photovoltaics (ACAP), documented in this 2017 Annual Report. According to EnergyTrend, the global manufacturing capacity for the Australian- invented and -developed PERC (Passivated Emitter and Rear Cell) technology grew by a massive 160.5% in 2017, reaching 42.38GW by the end of the year, about one-third of all capacity. With such high growth rates, PERC should account for the majority of photovoltaic manufacturing before 2020. ACAP researchers are working closely with a consortium of manufacturers and equipment suppliers to further increase PERC performance while reducing costs through patented hydrogenation technology. The buoyant mood created by the accelerating uptake of photovoltaics and of Australian Solar photovoltaics involves the direct technology was dampened by the sudden generation of electricity from sunlight, when passing in December of close colleague it shines upon devices known as solar cells. and solar pioneer, Professor Stuart Wenham. Silicon is the most common material used to Stuart has been involved with the UNSW make these photovoltaic cells, similarly to its group for over 34 years, playing a major role key role in microelectronics, although several in most of the group’s major achievements other photovoltaic materials are being actively over this period, including the development investigated. of the first 20% and 25% efficient silicon cells, the latter using PERC technology, the During 2017, photovoltaics reinforced its invention and commercialisation of the “buried position as the lowest cost option for electricity contact”, “semiconductor finger” and “Pluto” production yet developed. In August 2016, solar cells, as well as the hydrogenation bids were submitted for the long-term supply approaches mentioned above (see obituary at of electricity in Chile using solar photovoltaics end of Report). at US$29.10/MWh, appreciably lower than from any other bidding technology including This is the fifth annual ACAP report also coal, where the corresponding bid was nearly incorporating that of the Australia–US Institute twice as high at US$57/MWh (itself quite low for Advanced Photovoltaics (AUSIAPV), by international standards, with Bloomberg supported by the Australian Government estimating the cost of electricity from a new through the Australian Renewable Energy black coal plant in Australia in 2016 at an Agency (ARENA). ACAP encompasses the appreciably higher AU$120/MWh). In 2017, activities of Australian-based researchers appreciably lower bids were received in while, through synergistic research multiple power auctions. In September, a activities with US partners, AUSIAPV aims consortium led by Abu Dhabi’s renewable to significantly accelerate photovoltaic energy company Masdar submitted the lowest development beyond that achievable by bid to date for a project in Saudi Arabia, as Australia or the US individually. This objective OPEC’s top crude producer diversifies its is to be reached by leveraging development 1 — Australian Centre for Advanced Photovoltaics of “over the horizon” photovoltaic technology, confirmed at 34.5%, the highest ever for non- providing a pipeline of improved technology concentrated sunlight. In 2016, additional for increased performance and ongoing cost world-record results were confirmed for “thin- reduction. film” cells made from the compound CZTS (Cu ZnSnS ), based on “Earth abundant”, A second aim is to provide high quality training 2 4 relatively benign materials, and also for opportunities for the next generation of perovskite solar cells. An efficiency record of photovoltaic researchers, particularly through 9.5% was confirmed for a small area CZTS enhanced collaborations between Australian cell, with an efficiency of 18.0% independently and US researchers, with one targeted confirmed for a 1.2 cm2 perovskite cell, the outcome being to consolidate Australia’s highest ever for a cell of this size. position as the photovoltaic research and educational hub of the Asia-Pacific The tradition of world records was continued manufacturing region. in 2017 with the CZTS record improved to a new value of 11.0% and that for a perovskite ACAP/AUSIAPV came into being on 1 cell increased to 19.6%, the highest confirmed February 2013 after the signing of a Head efficiency reported for a perovskite cell Agreement between the University of New larger than 1 cm2 in area at that time. These South Wales (UNSW) and ARENA. During and several other key achievements during 2013, related Collaboration Agreements were 2017 are summarised in the highlight pages signed between UNSW and the other ACAP immediately following my report. More detailed nodes, Australian National University (ANU), results described in the body of this 2017 University of Melbourne (UoM), Monash Annual Report contributed to making 2017, University, University of Queensland (UQ) and once again, an extremely successful year for CSIRO (Materials Science and Engineering, both ACAP and AUSIAPV. Melbourne) and, additionally, with the ACAP industrial partners, Suntech Research and I would like to thank ARENA for its ongoing Development, Australia (SRDA) (partnership financial support and also for the very effective now transferred to Wuxi Suntech Power Co., involvement of ARENA personnel in supporting Ltd), Trina Solar Ltd, BlueScope Steel, BT the ACAP/AUSIAPV program, both informally Imaging, PV Lighthouse, Greatcell Pty Ltd and and via the ACAP National Steering Committee RayGen Resources. Our major international and the AUSIAPV International Advisory partners include the NSF-DOE Engineering Committee. I would additionally like to thank, Research Center for Quantum Energy and in particular, all researchers affiliated with the Sustainable Solar Technologies (QESST) and Institute for their contributions to the broad the US National Renewable Energy Laboratory range of progress reported in the following (NREL), as well as the Molecular Foundry pages. (Berkeley), Stanford University, Georgia Finally, I am pleased to be able to report that Institute of Technology and the University of ACAP/AUSIAPV has taken another major California, Santa Barbara. step